Java example source code file (JvmContextFactory.java)

This example Java source code file (JvmContextFactory.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

hashmap, jmx, jvmcontextfactory, map, object, snmp, snmppdu, snmpstatusexception, snmpuserdatafactory, util

The JvmContextFactory.java Java example source code

/*
 * Copyright (c) 2003, 2006, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */
package sun.management.snmp.util;

import com.sun.jmx.mbeanserver.Util;
import com.sun.jmx.snmp.agent.SnmpUserDataFactory;
import com.sun.jmx.snmp.SnmpPdu;
import com.sun.jmx.snmp.SnmpStatusException;

import java.util.Collections;
import java.util.HashMap;
import java.util.Map;


public class JvmContextFactory implements SnmpUserDataFactory {

    /**
     * Called by the <CODE>SnmpAdaptorServer adaptor.
     * Allocate a contextual object containing some user data. This method
     * is called once for each incoming SNMP request. The scope
     * of this object will be the whole request. Since the request can be
     * handled in several threads, the user should make sure that this
     * object can be accessed in a thread-safe manner. The SNMP framework
     * will never access this object directly - it will simply pass
     * it to the <code>SnmpMibAgent within
     * <code>SnmpMibRequest objects - from where it can be retrieved
     * through the {@link com.sun.jmx.snmp.agent.SnmpMibRequest#getUserData() getUserData()} accessor.
     * <code>null is considered to be a valid return value.
     *
     * This method is called just after the SnmpPduPacket has been
     * decoded.
     *
     * @param requestPdu The SnmpPduPacket received from the SNMP manager.
     *        <b>This parameter is owned by the SNMP framework and must be
     *        considered as transient.</b> If you wish to keep some of its
     *        content after this method returns (by storing it in the
     *        returned object for instance) you should clone that
     *        information.
     *
     * @return A newly allocated user-data contextual object, or
     *         <code>null
     * @exception SnmpStatusException If an SnmpStatusException is thrown,
     *            the request will be aborted.
     *
     * @since Java DMK 5.0
     **/
    public Object allocateUserData(SnmpPdu requestPdu)
        throws SnmpStatusException {
        return Collections.synchronizedMap(new HashMap<Object, Object>());
    }

    /**
     * Called by the <CODE>SnmpAdaptorServer adaptor.
     * Release a previously allocated contextual object containing user-data.
     * This method is called just before the responsePdu is sent back to the
     * manager. It gives the user a chance to alter the responsePdu packet
     * before it is encoded, and to free any resources that might have
     * been allocated when creating the contextual object.
     *
     * @param userData The contextual object being released.
     * @param responsePdu The SnmpPduPacket that will be sent back to the
     *        SNMP manager.
     *        <b>This parameter is owned by the SNMP framework and must be
     *        considered as transient.</b> If you wish to keep some of its
     *        content after this method returns you should clone that
     *        information.
     *
     * @exception SnmpStatusException If an SnmpStatusException is thrown,
     *            the responsePdu is dropped and nothing is returned to
     *            to the manager.
     *
     * @since Java DMK 5.0
     **/
    public void releaseUserData(Object userData, SnmpPdu responsePdu)
        throws SnmpStatusException {
        ((Map<?, ?>)userData).clear();
    }


    public static Map<Object, Object> getUserData() {
        final Object userData =
            com.sun.jmx.snmp.ThreadContext.get("SnmpUserData");

        if (userData instanceof Map<?, ?>) return Util.cast(userData);
        else return null;
    }

}